<style scoped>
  .list-item {
    display: inline-block;
    margin-right: 10px;
  }

  /* 进入/离开的过渡样式 */
  .list-enter-active, .list-leave-active {
    transition: all 1s;
  }

  /* 隐藏时的样式 */
  .list-enter, .list-leave-to  {
    opacity: 0;
    transform: translateY(30px);
  }
</style>


<template>
  <div id="list-demo" class="demo">
  <button v-on:click="add">Add</button>
  <button v-on:click="remove">Remove</button>
  <transition-group name="list" tag="p">
    <span v-for="item in items" v-bind:key="item" class="list-item">
      {{ item }}
    </span>
  </transition-group>
</div>
</template>

<script>
export default {
  name: 'App',
  data () {
    return {
      items: [1,2,3,4,5,6,7,8,9],
      nextNum: 10
    }
  },
  methods: {
    randomIndex: function () {
      return Math.floor(Math.random() * this.items.length)
    },
    add: function () {
      this.items.splice(this.randomIndex(), 0, this.nextNum++)
    },
    remove: function () {
      this.items.splice(this.randomIndex(), 1)
    },
  }
}
</script>

